JP2000108837A - Device and method for monitoring mass and density of fluid in sealed container and vehicle air bag system incorporated with such device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor mass and density of a pressurized fluid by providing density such as a density sensor moves to a first position in a container when fluid density is prescribed density and moves to a second position in the container when the fluid density is lower than the prescribed density. SOLUTION: An indicator 34 displays whether fluid density in a container 10 is lower or higher than density of a density sensor 24 on the basis of a frequency of a transmitter 30 decided by a frequency measuring device 32. When the fluid desnity is smaller than ?density of the density sensor 24, the density sensor 24 is positioned adjacently to the bottom part of a sensing chamber 18. When the fluid density is larger than density of the density sensor 24, the density sensor 24 floats up to a position adjacent to the top part of the sensing chamber 18. The indicator 34 has output for showing whether the fluid density is lower or higher than density of the density sensor 24 to thereby monitor density and mass of fluid pressurized in the container 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an apparatus for monitoring the density of a fluid in a closed container and therefore the mass quality of the fluid. The present invention further provides:
The present invention relates to a method for filling a container to a predetermined mass using a fluid. Further, the present invention relates to an improved airbag system for a motor vehicle. The airbag system includes a sensor and an indicator for providing an indication of a leak of propellant gas to fill the airbag.

[0002]

2. Description of the Related Art The density of a fluid in a closed volume of a closed container is proportional to the mass of the fluid in the closed container. Therefore, by monitoring the fluid density, the mass of the fluid in the certain volume can be determined. The density of the fluid under high pressure in the closed container is preferably monitored without entering the closed container in order to avoid leakage of the fluid from the closed container.

[0003] In many applications, the monitoring is accomplished by providing an indication of whether the density and thus the mass is sufficiently high, ie, whether the density or mass is above or below a predetermined value. It only needs to be provided. In such applications, the use of one device to monitor two conditions is appropriate. In other applications, it may be desirable to have more precise monitoring to provide a more accurate indication of fluid density and fluid mass.

[0004]

Many vehicle airbag systems include a propellant gas canister for inflating the airbag if a collision or impact is sensed. By monitoring the mass of this propellant gas, it should be ensured that sufficient gas mass is present so that the airbag can be properly inflated if a collision or impact is sensed. . Monitoring propellant gas density to ensure that the propellant gas maintains at least a specified density is one way to monitor gas mass.
A drop in the density of the propellant gas can indicate a drop in the mass of the gas in the container. The drop in the mass of the gas may be caused by a gas leak from the container. Due to such a gas leak, the airbag system of the vehicle no longer has enough gas, so that the airbag does not inflate sufficiently during a collision. As many motor vehicles have been used for several years without activation of the airbag system, propellant gases may have leaked over the life of the vehicle or airbag system. Therefore, monitoring the density of the propellant gas is desirable to be able to detect that gas leakage has reached an inappropriate level.

[0005] Containers for pressurized fluids that are expected to have a long service life are preferably filled with a fluid mass that exceeds the lowest acceptable mass. As a result, despite a slight leak, the container:
Maintain the lowest acceptable mass for at least the expected life, or at least for a significant portion of the expected life. By monitoring (ie, monitoring) the fluid density within the container, the mass can be monitored. It is desirable to be able to monitor two fluid density levels of the fluid in the container. First
Is the density level corresponding to the lowest acceptable mass of fluid in said container. The second density level is the density level corresponding to the container fluid to be filled when manufactured or refilled. In other applications, it may be desirable to monitor several density levels.

[0006]

SUMMARY OF THE INVENTION In one aspect, the present invention relates to an apparatus for monitoring the mass and density of a pressurized fluid in a closed container (in other words, a closed container). A density sensor is provided in the closed container. When the fluid density is at least at a predetermined density corresponding to a predetermined mass of fluid in the closed container, the density sensor has a density such that it moves to a first location in the closed container. . Moreover, when the density of the fluid is lower than the predetermined density, the density sensor has a density such that it moves to a second position in the closed container. A detector monitors the location of the density sensor within the closed container.

[0007] In another aspect, the present invention includes the apparatus for monitoring the density and mass of pressurized fluid in a closed container provided in a vehicle airbag system. In the vehicle airbag system, the apparatus may include a pressurized propulsion device having a mass sufficient to allow the container to inflate the airbag sufficiently when an impact (or collision) is sensed. It indicates whether or not a fluid (ie, a pressurized jetting fluid) is included. The airbag system comprises an airbag, an impact sensor (in other words, a collision sensor)
And holding a predetermined mass of propulsion fluid at a certain constant pressure,
A sealed container of a certain volume (ie, a closed container), wherein the fluid can have at least a predetermined density. The sealed container has a valve connected to the airbag and the impact sensor. When the impact sensor detects an impact (or collision), the valve opens to release the propulsion fluid from the sealed container into the airbag, thereby inflating the airbag. be able to. The density sensor provided in the sealed container is provided when the fluid has at least a predetermined density, and therefore, when at least a predetermined mass of propulsion fluid is in the container, the density sensor is configured to be It has a density such that it floats on the pressurized propellant fluid in a closed container. If the mass of the fluid is less than the predetermined mass, and thus the density of the fluid is lower than the predetermined density, the density sensor sinks in the fluid. A detector monitors (ie, monitors) the position of the density sensor. Indicator (ie,
Display) displays the monitored position of the density sensor. Thus, if the density sensor sinks into the propulsion fluid, the indicator will indicate that the airbag system requires maintenance.

[0008] Yet another feature of the present invention is a method of filling a sealed container of a certain volume with a predetermined mass of fluid. A density sensor is provided on the container. The density sensor has a density such that the density sensor floats on the fluid when the fluid has a density corresponding to the predetermined mass of the fluid in the volume of the sealed container, If the fluid has a lower density, the density sensor has a density such that it sinks into the fluid. In this way,
The density sensor is adjacent to the bottom of the container when a filling process (filling process) starts. When the container is filled to the predetermined mass, the density sensor rises to a position adjacent to the top of the container. The position of the density sensor is monitored,
When the density sensor rises, the filling is stopped.

These and other features and advantages of the present invention are:
From the statements and claims set forth in detail below,
It will become apparent from a consideration of the accompanying drawings. In the drawings, similar elements are provided with the same reference signs.

[0010]

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a container (ie,
(Container) 10 is illustrated. The container 10 has an inlet / outlet (ie, inlet / outlet) 12
have. Inlet / outlet 12 is controlled by valve 14. When the valve 14 is opened, fluid can be introduced into or withdrawn from the container 10. When the valve 14 is closed, the container 10 is substantially liquid tight. However, as a practical matter, some of the pressurized fluid may leak out of the container 10 slowly, even with the valve 14 sealed.

The interior of the container 10 is divided by a partition 20 into a main chamber 16 and a sensing chamber 18. The partition 20 has an opening 22. The opening 22 allows fluid to flow between the main chamber 16 and the sensing chamber 18. A density sensor 24 is positioned within the sensing chamber 18. The density sensor 24 has a size (size) that cannot pass through the opening 22. Sensing chamber 18
Preferably has a cross section that is slightly larger than the cross section of the density sensor 24 to substantially limit vertical movement of the density sensor 24.

The fluid to be monitored (ie, monitored) is introduced into container 10 via valve 14 and inlet / outlet 12. Initially, density sensor 24 is adjacent to the bottom of sensing chamber 18. As the mass of the fluid in the container 10 increases, the density of the fluid increases. When the density of the fluid becomes greater than the density of the density sensor 24, the density sensor 24 floats to a position adjacent to the top of the sensing chamber 18.

A sensing coil 26 is positioned adjacent the top of sensing chamber 18. The sensing coil 26 is
Oscillator (in other words, oscillator, vibrator, vibrator) 3
0, so that the oscillation frequency of the oscillator 30 (in other words, the oscillation frequency and the oscillation frequency) can be controlled. The density sensor 24 includes a material that includes sufficient iron (or ferrous) so that the density sensor 24 is adjacent to the top of the sensing chamber 18 from a location adjacent to the bottom of the sensing chamber 18. When moved into position, the inductance of the sensing coil 26 can be changed. The oscillation frequency of the oscillator 30 (in other words, the oscillation frequency) is determined by the inductance of the sensing coil 26. As a result, the oscillation frequency of oscillator 30 indicates whether density sensor 24 is near the top of sensing chamber 18 or near the bottom of sensing chamber 18. The oscillator 30 includes a frequency measuring device 32
The output unit (output) of the frequency measuring device 32 is connected to an indicator (that is, an indicator) 34.

Thus, based on the frequency of the oscillator 30 determined by the frequency measuring device 32, the indicator (ie, indicator) 34
It indicates whether the fluid density inside is below or above the density of the density sensor 24. If the fluid density is less than the density of density sensor 24, density sensor 24 is positioned adjacent the bottom of sensing chamber 18. As a result, the density sensor 24
6 has little or no effect on the inductance. Fluid density is density sensor 2
If greater than 4, the density sensor 24 floats to a position adjacent to the top of the sensing chamber 18. As a result, the density sensor 24 has a greater effect on the inductance of the sensing coil 26. The inductance of the sensing coil 26 further determines the frequency of the oscillator 30. Therefore, the indicator 34 is actually the oscillator 3
It can have an output indicating a frequency of zero, but indicating whether the density of the fluid is below or above the density of the density sensor 24. The fluid density is
Because it is proportional to the mass of the fluid in the sealed container 10, the indicator 34 can indicate whether the mass is above or below a predetermined level.

Until the density sensor 24 floats on the fluid, the container 10 can be filled with the fluid. As long as the fluid density is equal to or greater than the density of the density sensor 24, the density sensor 24
Keeps floating in the fluid. Fluid density is density sensor 24
If the density sensor 24 falls below the density of
Sinks in fluid. This changes the inductance of the sensing coil 26, and consequently changes the oscillation frequency (frequency, oscillation frequency) of the oscillator 30. The change in frequency is
Determined by a frequency measurement circuit (frequency measurement device) 32 and indicated by an indicator 34. The density sensor 24 is provided when the fluid has at least a predetermined density.
When the density sensor 24 has a density such that it floats on the fluid in the sealed container 10 and the density of the fluid is smaller than the predetermined density, the density sensor 24 has a density such that it sinks in the fluid. Is selected.

The indicator 34 can be of any type (type or type). For example, the indicator 34 can be a two-state indicator, such as a light emitter (or light source). A two-state indicator, such as the illuminant, is provided by the density sensor 24
Is not energized (or biased) when adjacent to the top of the However, a two-state indicator, such as a light emitter,
When the density sensor 24 is adjacent to the bottom of the sensing chamber 18, it can be energized (or energized) to indicate an alarm. In this way, it can be indicated that the mass of the fluid in the container 10 has dropped below an acceptable level. Such a descent may be caused by a leak from the container 10.

Alternatively, the apparatus of the present invention can monitor (ie, monitor) a fluid whose mass and, therefore, density is maintained below (below) a predetermined level. In such an application, the density sensor 24 has a density such that the density sensor 24 remains at the bottom of the sensing chamber 18 as long as the fluid density is below the predetermined density, and the fluid density is less than the predetermined density. When increasing to a level above the density, the density sensor 2
4 has a density such that it rises to a position adjacent to the top of the sensing chamber 18. By changing the position of the density sensor 24, the inductance of the sensing coil 26 is changed, and the frequency of the oscillator 30 is changed. When the frequency detector (frequency measurement device) 32 detects this change in frequency, the frequency detector 32 supplies an output (output) to the indicator 34 to increase the density and to reduce the density in the sealed container 10. An increase in the mass of the fluid can be indicated. In such applications, indicator 3
4 may be a light emitter (or light source) that is energized when the density sensor 24 is adjacent to the top of the sensing chamber 18 but not energized when the density sensor 24 is adjacent to the bottom of the sensing chamber 18.

Alternatively, or in addition, the output of frequency detector 32 can be used to activate a control device (ie, control device), such as controller 35 shown in FIG. For example, if the device is monitoring a container fluid that should maintain the density of the fluid, and hence the mass below a predetermined level, an increase in density above the predetermined level is detected. In response to the output from the frequency detector 32, the valve can be operated to discharge a certain amount of fluid.

The density sensor 24 includes a ball (spherical body),
For example, it is preferably a hollow ball. The interior of the hollow ball is depressurized or contains a gas having a density lower than a predetermined density to be sensed. To affect the sensing coil 26 and affect the oscillation frequency of the oscillator 30, the density sensor 24 as a sensing device must include a material that includes iron (ie, consists of iron). The density sensor 24 can be formed from a (ferrous) material including iron. Alternatively, the density sensor
Coating (coating) with iron coating agent (coating)
It may be formed of a material not containing iron (non-ferrous material). Similarly, density sensors can be formed from non-ferrous materials, including ferrous materials. The non-ferrous material can be formed from a polymer (polymer) material. in this case,
Coating the density sensor with a sealing material
Then, it is possible to prevent the pressurized fluid from entering.

FIG. 2 illustrates a modification of the present invention, in which two density sensors 24 are provided.
a, 24 b are provided in the sensing chamber 18.
The two density sensors 24a, 24b have different densities. Thus, as shown in FIG. 2, the density sensor 24a has a lower density than the density sensor 24b. As a result, when the fluid is introduced into the interior of the container 10, the mass of the fluid and thus the density of the fluid increases until the first density sensor 24 a rises to a position adjacent to the top of the sensing chamber 18. Then, the density sensor 24b is connected to the sensing chamber 1
8 to a position adjacent to the top. As each density sensor 24a, 24b approaches the top of the sensing chamber 18, the inductance of the sensing coil 26 changes. Thus, when the density of the fluid in the container 10 is low and the two density sensors 24a, 24b are adjacent to the bottom of the sensing chamber 18, the oscillator 30 oscillates at the first frequency. Oscillator 30 also oscillates at a second frequency when density sensor 24a is adjacent the top of sensing chamber 18 while density sensor 24b remains adjacent the bottom. Also, two density sensors 24a, 24b
Is adjacent to the top of the sensing chamber 18, the oscillator 30 oscillates at a third frequency. This is useful in manufacturing a container filled with fluid or refilling (ie, refilling) a container with fluid. The density sensor 24b floats, so that the two density sensors 24b
When a, 24b is adjacent to the top of the sensing chamber 18,
The density sensor 24b can have a density such that the container 10 is filled with the desired level of fluid. At that time, the filling is stopped. Density sensor 24a
Can have a density equal to the minimum acceptable density for the fluid in the container 10 corresponding to the minimum acceptable fluid mass. Thus, the container 10 is filled until two density sensors 24a, 24b float to a position adjacent to the top of the sensing chamber 18 due to manufacturing or replenishment. At that time, when the fluid leaks from the container 10 or when the fluid is used from the container 10, the fluid density becomes the point where the density sensor 24 a sinks in the sensing chamber 18.
When lowered, the indicator 34 indicates that the container 10 is no longer acceptable. Density sensor 24a may thus indicate that excess fluid has leaked during the life of container 10, or may provide container 10 with a point at which it should be refilled (ie, refilled) with fluid. Indicate that fluid from 10 has been utilized, or until container 10 is removed from service (i.e., service or maintenance) (i.e., container should no longer be used for monitoring). Indicates that the fluid from was used.

FIG. 3 illustrates another modified embodiment of the present invention. In this embodiment, a plurality of density sensors are provided in sensing chamber 18. Specifically, five density sensors 24a-24e are shown. Each density sensor 24a-24e has a different density, and as the mass of fluid in container 10 increases, the number of density sensors floating near the top of sensing chamber 18 increases. Each floating density sensor increases the effect on the inductance of the sensing coil 26 and, consequently, the frequency on the oscillator 30. Therefore, the frequency of the oscillator 30 is
It indicates which of the six mass ranges the contents of 0 are in.

FIG. 4 illustrates the density monitoring device of FIG. 1 used to monitor (ie, monitor) the propellant gases of a vehicle airbag system. The inlet / outlet (ie, inlet / outlet) 12 of the container 10 has a valve 14a. The valve 14a connects the container 10 to the vehicle airbag 38. The valve 14a includes an airbag controller 39 and an impact sensor (that is, a collision sensor) 3
And 6. In this way, if the vehicle to which the vehicle airbag system is attached experiences a collision or other impact, the impact sensor 36 applies an input to the airbag controller 39, thereby opening the valve 14a, The propelling gas in the container 10 inflates the vehicle airbag 38.

The density sensor 24 senses the density of the propellant gas in the container 10 and controls the oscillation frequency of the oscillator 30. As long as the airbag system contains a sufficient mass of propellant gas,
The density sensor 24 floats near the top of the sensing chamber 18. If the propellant gas in the container 10 has leaked to a point where the vehicle airbag does not expand sufficiently during the collision, the density of the propellant gas is determined by the density sensor 2.
4 has descended to a point where it sinks to a position adjacent to the bottom of sensing chamber 18. As a result, the oscillation frequency of the oscillator 30 changes and the indicator 34 is activated. Indicator 34 may be a light emitter (or light source) provided on the vehicle dashboard, thereby alerting the vehicle operator (vehicle occupant) that the airbag system needs service (service, maintenance, etc.). Can be.

The ball shape is just one shape that the density sensor 24 can take. For example, a circular (annular) sieve form may be used. Similarly, container 10 with internal partition 20 is only one form of container capable of maintaining a fluid under pressure. A cylindrical container may be utilized with a density sensor having a diameter slightly smaller than the diameter of the cylindrical container. FIG. 5 illustrates the container 10a. The container 10a includes a main chamber 16a and a sensing chamber 18a as described below, instead of an internal partition provided in the container 10. The main chamber 16a and the sensing chamber 18a can be in fluid communication with each other through a passage 22a.
Are provided at the upper end and the lower end of the opening 20a passing through the container. Therefore, the container 10a
Is a one gallon plastic jug with a hollow handle (handle).
tic jug). Coil 26
a passes through the opening 20a and surrounds the outside of the sensing chamber 18a. The density sensor 24f is a rectangular sensor. The rectangular sensor has a length substantially equal to the vertical length of the sensing chamber 18a covered by the coil 26a, and has a width slightly smaller than the internal cross-section of the sensing chamber 18a. ing. As a result, the longer axis of the density sensor 24f is maintained substantially vertically. Container 1
When the fluid mass in Oa increases, the fluid density increases,
The density sensor 24f rises in the sensing chamber 18a. As the density sensor 24f rises, the number of turns of the coil 26a surrounding the density sensor 24f gradually increases, thereby increasing the influence on the inductance of the coil 26a. As a result, when the fluid mass in the container 10a increases, the frequency of the oscillator 30 gradually changes. When the density sensor 24f has completely penetrated its multi-turn coil 26a, the frequency of the oscillator reaches its limit. The change in the frequency of the oscillator 30 is indicated by an indicator 34, whereby
An increase in fluid mass in the container 10a is shown. Alternatively, if the fluid leaks from the container 10a, the fluid density decreases and the density sensor 24f
6a descends from inside. Thereby, the frequency of the oscillator 30 changes.

Thus, the present invention can monitor the density and mass of a pressurized fluid in a closed container and display a range of fluid density or a range of fluid mass. The present invention includes a method of filling a container with a fluid to a predetermined mass or density. Further, the present invention relates to an airbag propellant (ai)
A vehicle that can indicate that the mass of r bag propellerant has dropped to an unacceptable level
An air bag system is provided. Although the present invention has been described with reference to preferred embodiments, various reconfigurations, alternatives, and exchanges can be made, and with various reconfigurations, alternatives, and exchanges,
It falls within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a first embodiment of an apparatus according to the present invention for monitoring the mass of a pressurized fluid in a closed container.

FIG. 2 is a partial schematic view of a second embodiment of the device according to the invention for monitoring the mass of pressurized fluid in a closed container.

FIG. 3 is a partial schematic view of a third embodiment of the device according to the invention for monitoring the mass of a pressurized fluid in a closed container.

FIG. 4 is a schematic block diagram of a vehicle airbag system according to the present invention, including a device for monitoring the mass of propulsion fluid of the airbag system.

FIG. 5 is a schematic block diagram of yet another embodiment of an apparatus according to the present invention for monitoring the mass of a pressurized fluid in a closed container.

[Explanation of symbols]

10 container 10 12 inlet / outlet (ie inlet /
Outlet) 14 Valve 14 14a Valve 14a 16 Main chamber 16a Main chamber 18 Sensing chamber 18a Sensing chamber 20 Partition 22 Opening 20a Opening 22a Passage 24 Density sensors 24a, 24b
Density sensor 24a-24e Density sensor 24f Density sensor 26 Sensing coil 26a Coil 30 Oscillator 32 Frequency measuring device (frequency measuring circuit, frequency detector) 34 Indicator (display) 35 Controller 36 Impact sensor (that is, collision sensor) 38 Vehicle air Back 39 Airbag controller

Claims (13)

[Claims] 1. A monitoring device for monitoring the mass and density of a fluid in a sealed container, said monitoring device comprising: under a pressure that causes a predetermined mass of fluid to have at least a predetermined density; A sealed container for holding the fluid, and a density sensor provided in the sealed container, wherein the density sensor is configured to be closed when the fluid has at least the predetermined density. Having a density such that it moves to a first position in the container,
In addition, when the density of the fluid is lower than the predetermined density, the fluid has a density such that the fluid moves to a second position in the sealed container. A monitoring device comprising a detector for monitoring the position of the density sensor in a container. 2. The monitoring device according to claim 1, wherein the sealed container has a main chamber and a sensing chamber, wherein the main chamber and the sensing chamber are in fluid communication with each other; The monitoring device, wherein the density sensor is provided in the sensing chamber. 3. The monitoring device according to claim 1, wherein the density sensor includes a floating device. 4. The monitoring device according to claim 3, wherein the floating device has a density such that it floats in the fluid in the sealed container when the fluid has a density at least equal to the predetermined density. Wherein the fluid has a density lower than the predetermined density,
A monitoring device having a density so as to sink in the fluid. 5. The monitoring device according to claim 1, further comprising an indicator responsive to the detector for indicating a monitored position of the density sensor within the sealed container. A monitoring device characterized in that: 6. The monitoring device according to claim 1, wherein the density sensor includes a material including iron, and the detector is an oscillator circuit, responsive to a position of the density sensor. A monitoring device comprising: an oscillator circuit having a sensing coil for controlling the frequency of the oscillator circuit; and a frequency detector for detecting the frequency of the oscillator circuit. 7. An air bag system for a vehicle, comprising: an air bag; an impact sensor; and a pressurized fluid having a certain volume and a sufficient mass to hold the air bag properly. A sealed container that can be inflated to a closed container, wherein the sealed container has a valve connected to the airbag and the shock sensor, and the valve is operated by the shock sensor. The airbag system for the vehicle may also open in response to sensing a collision and release the fluid from the sealed container into the airbag to inflate the airbag. A density sensor provided in a sealed container, wherein the density sensor indicates that the sealed container has at least the sufficient When holding a mass of fluid, the container holds a fluid having a density such that it floats on the fluid in the closed container, and the container holds a smaller mass of fluid than the sufficient mass of fluid. An airbag system for the vehicle, further comprising: a detector for monitoring a position of the density sensor in the sealed container; An indicator for indicating a monitored position of the density sensor within the sealed container in response to a container. 8. The airbag system according to claim 7, wherein the sealed container has a main chamber and a sensing chamber, wherein the main chamber and the sensing chamber are in fluid communication with each other. The airbag system, wherein the density sensor is provided in the sensing chamber. 9. The air bag system according to claim 8, wherein the sealed container has an internal partition that divides the inside of the sealed container into the main chamber and the sensing chamber. An airbag system characterized by the following. 10. The airbag system according to claim 7, wherein the density sensor comprises a material including iron, and the detector is an oscillator circuit responsive to a position of the density sensor. An airbag system comprising: an oscillator circuit having a sensing coil for controlling the frequency of the oscillator circuit; and a frequency detector for detecting the frequency of the oscillator circuit. 11. An airbag system for a vehicle, comprising: an airbag, an impact sensor, a certain volume, and a fluid having a predetermined mass and holding the fluid at a pressure at which the density becomes at least a predetermined density. And a sealed container, wherein the sealed container has a valve connected to the airbag and the shock sensor, and the valve is responsive to a collision detection by the shock sensor. Open and release the fluid from the sealed container into the airbag to inflate the airbag.The airbag system for the vehicle also includes A density sensor provided, wherein the density sensor is provided when the fluid has at least the predetermined density. Having a density such that it floats in the fluid in the container, and has a density such that it sinks in the fluid when the density of the fluid is smaller than the predetermined density; and The bag system further includes a detector for monitoring a position of the density sensor within the sealed container, and a monitored position of the density sensor within the sealed container in response to the detector. An airbag system for a vehicle, comprising: a display for displaying a vehicle. 12. The airbag system according to claim 11, wherein the sealed container has a main chamber and a sensing chamber, wherein the main chamber and the sensing chamber are in fluid communication with each other. The airbag system, wherein the density sensor is provided in the sensing chamber. 13. The airbag system according to claim 12, wherein the sealed container has an internal partition that divides the inside of the sealed container into the main chamber and the sensing chamber. An airbag system characterized by the following.